Ubuntu – GRE Tunnel

Creating a tunnel on Ubuntu

Edit /etc/network/interface file and add this code

auto gre1
iface gre1 inet static
    address 
    netmask 
    pointopoint 
    pre-up iptunnel add gre1 mode gre local  remote  ttl 255
    up ifconfig gre1 multicast
    post-down iptunnel del gre1

You might also need to “modprobe ip_gre” in some cases before activating the tunnel.